Questions and negation
Negation
Say no, I don't, and don't do it.
The negative word goes right before what it negates, and nothing else in the sentence changes. There's no helper like English do. The word you choose depends on what follows: ไม่ negates verbs and adjectives, while a noun usually needs ไม่ใช่, “is not”.
subject+ไม่+verb
I don't eat meat.
A useful sentence for vegetarians from the first day. เนื้อ often means beef in particular.
Not spicy, please.
I'm not Thai.
Don't put chilli in.
Common mistake
Don't put ไม่ straight before a noun. “I'm not Thai” is ผมไม่ใช่คนไทย. ผมไม่คนไทย sounds like an unfinished sentence.
Practise
Kai says
Thai verbs don't change their endings for past and future. Context and words such as จะ, a future marker, tell you when something happens.